An ink jet head of an ink jet printer, which is an example of a fluid ejection device, ejects ink drops in a dot matrix onto a surface of a recording medium, such as plain paper, from a minute nozzle hole, to form, for example, characters or figures. Since the ink jet head has to eject each ink drop at a high speed and precisely towards a target from the nozzle hole, problems, such as clogging, at the nozzle hole undesirably lowers landing precision of the ink drops varies ink ejection amount, resulting in lowered print quality.
To eliminate such problems, purging is performed to periodically discharge ink from the nozzle hole, to thereby remove foreign matter, such as air bubbles, solidified ink, or viscosity-increased ink, existing in the nozzle hole. When the printer is not used, the nozzle face is covered with a cap to protect the nozzle hole from drying of the ink in the nozzle hole and adherence of dust to the nozzle hole.
In the purging, the nozzle face of the ink jet head, where the nozzle hole is disposed, is covered with a cap, and ink in an ink flow path of the ink jet head and in the nozzle hole is sucked or ejected, to remove any foreign matter in the ink flow path of the ink jet head and in the nozzle hole. In protecting the nozzle hole, the nozzle face, where the nozzle hole is disposed, is covered with the cap to protect the nozzle hole from adherence of, for example, dust; and to prevent drying of the ink by maintaining the humidity in the cap. This way, the ink in the ink nozzle are prevented from being increased in viscosity and being solidified.
To increase the volume of ink sucked from the nozzle hole in the purging, the cap is provided with an absorber that absorbs ink. In general, the absorber is accommodated in the cap supported by a cap holder, and is secured by, for example, a holding member. For example, Japanese Unexamined Patent Application Publication No. 2004-142422 (page 19, FIG. 24) discloses a cap including a cap base, an absorber accommodating portion, a function liquid absorber, an absorber holding member, a sealing member, and a seal securing member. The absorber accommodating portion is formed at the cap base. The function liquid absorber fills the interior of the absorber accommodating portion. The absorber holding member holds the function liquid absorber. The seal securing member secures the sealing member to the cap base.
However, since the cap for the ink jet head is arranged such that a peripheral edge of the absorber holding member is held by the sealing member and that the sealing member is secured to the cap base by the seal securing member, a large number of parts is required and a large number of assembling steps is required. Further, when securing the absorber holding member, thermal caulking or an ultrasonic welding may be required. Therefore, for example, dimensional precision of the securing position of the absorber holding member with respect to the cap base is required, thereby lowering production efficiency and preventing cost reduction.